This applicant is a continuation of U.S. patent application Ser. No. 09/481,451 filed Jan. 11, 2000, now U.S. Pat. No. 6,797,306, which claims, under 35 U.S.C. §119(e), the benefit of priority of the filing of Mar. 18, 1999 of U.S. Provisional Patent Application filed on the aforementioned date having the title “Roller Manifold For Forming A Continuous Sheet Of Viscous Material” listing Kenneth R. Fahs, Franco X. Milani, and Shawn L. Owens as inventors and having Ser. No. 60/125,195, the entire contents of which are incorporated herein by reference.
The present invention is directed to a method and apparatus for forming a continuous sheet of a molten material with particularly viscous, sticky properties. This molten material may be moldable, plasticized or a food product such as cheese. More specifically, the invention includes a manifold that discharges the molten material in a continuous layer upon the surface of a casting belt. This manifold comprises a roller, a hollow chamber with at least one open side and at least one inlet into the chamber.
Material such as processed cheese products present some difficulties in cutting or slicing because such material tends to cling to the cutting surfaces. For this reason, a process was developed in which such a material is melted and extruded into a thin sheet upon a surface such as a moving belt. In such a process, molten cheese is fed into a manifold, which distributes the molten cheese in a layer onto a continuously moving endless belt, which is commonly called a casting belt. Such a process, and the apparatus used in such a process, is described, for example, in U.S. Pat. Nos. 5,527,551 and 5,573,805, the entire content of which are incorporated herein by reference.,
A standard manifold that may be used in such a process is also described, for example, in U.S. Pat. No. 4,790,242. In prior art manifolds, cheese is distributed from the manifold onto the casting belt. A fixed bar known as a “nose bar” forms part of the manifold. The manifold distributes the cheese onto the casting belt between the nose bar and the surface of the casting belt (i.e., the space between the nose bar and the surface of the casting belt defines the thickness of the layer or film of cheese). Pressure is provided, through suitable pumps, to force the cheese to extrude between the surface of the belt and the nose bar. Since the casting belt is moving, the cheese is carried downstream of the nose bar on the surface of the casting belt thereby forming a continuously moving sheet of cheese. The sheet of cheese is further processed downstream in a manner known in the art. A standard manifold is divided into an upper and lower compartment and may even be further divided into a number of compartments in order to distribute evenly the pressure building up from the material coursing through the manifold. The manifold of the present invention, however, requires only one interior space, although additional compartments are not precluded from the invention.
Materials such as processed cheese products are now being created with more “extreme” textures. These “extreme” textures tend to be stickier and more viscous than other types of cheese. Because of this stickiness, it becomes more difficult to form a continuous sheet of material using the process and apparatus described in the prior art since the stickier material clogs the chambers of prior art manifolds and tends to tear while extruding onto the casting belt from a “nose bar” or other such standard manifold. The viscosity also affects the processing because more viscous materials tend to tear as they exit from the nose bar.
Viscosity is a measurement of the flow properties of a product. Viscosity can be defined as the ratio of the “shear force” applied to a material and the amount that the material is “deformed” by this force. The deformation of the material is expressed as the “rate of shear”. Therefore, viscosity is the relationship between shearing stress and rate of shear. Viscosity is temperature dependent and typically decreases as the temperature rises.
TABLE 1 below lists some common fluids and their viscosities, in addition to the viscosities of some of the products that could be processed using the method and apparatus of the current invention.
TABLE 1FLUIDCP at 0° C.CP at 20° C.CP at 30° C.water1.791.00Milk, whole4.282.12Sucrose solution60.2(60%)Molasses6600Olive oil84.0Soybean oil40.6
Therefore, a number of characteristics are desirable for a manifold dispensing such sticky or viscous material. Such a manifold must have a capability for receiving the starting material under pressure and distributing it evenly along the full length of the manifold and upon the casting belt. This distribution must be accomplished continuously to accommodate the high rate at which the material flows through the manifold. The manifold must facilitate distribution of the material in such a way that the material forms continuous sheets and does not tear as it is being deposited on the belt. The manifold should be easily assembled and disassembled for cleaning purposes. Finally, it would be advantageous if the manifold were interchangeable with a standard/prior art manifold (or other suitable manifold) so that more than one variety of manifold could be used with the same casting line and more than one variety of starting material could be processed.
The process by which such sticky, viscous starting material flows through the manifold should also accommodate the stickiness of the material. The material should flow through the manifold in such a manner and at a rate that is suitable for commercial processing and such that the manifold is not clogged.
Therefore, in view of the above, it is an object of the present invention to provide an apparatus and method which efficiently forms a continuous sheet of material from such a sticky or viscous starting material.
Another object of the present invention is to provide a manifold that accommodates such viscous starting material with minimal clogging and tearing.